Evaluating Web Software Reliability Based on Workload and Failure Data Extracted From Server Logs CSI518 – Group 1

Definition of Reliability The increasing usage of Web software systems and attraction of society to the Web makes reliability of Web systems more important. reliability What is reliability for Web applications? The reliability for Web applications can be defined as the probability of failure-free Web operation completions. [1] Failure is “the event of a system deviating from its specified behavior like obtaining or delivering information”. [2]

Failure Sources Failures are caused from the following sources: Host, network or browser failures: computer systems, network or software failures, etc. Source content failures: missing, unaccessible files, Javascript errors, etc. User errors: improper usage, mistyped URLs. [1]

Project Goal ● This project concentrates on the minimizing of source content failures to strengthen the reliability of Web applications. With this project, we try to accomplish the following goals as a team: Attempt to extend work on testing the reliability of websites. Gain experience doing a research project

Workload Analysis To analyze the reliability of web systems, we're gonna use the access logs and error logs under the title of server logs. Failure information alone is not enough for assess the reliability of system so measuring the workload is also necessary. To measurements for workload are byte count, user count, session count and number of hits.

Workload Measures Hit Count: Each hit shows the specific request to a web server. Misleading because individual hits show high variability. Byte Count: Number of bytes transferred gives finer granularity than hit count. User Count: Treat each client IP address as one user. Disadv: coarse granularity. Session Count: Number of user sessions can be calculated by IP address and access times using time limits per user [3].

References [1] J.Tian, S.Rudraraju, Z.Li, “Evaluating Web Software Reliability Based on Workload and Failure Data Extracted from Server Logs”,2004. [2] T.Huynh, J.Miller, “Another viewpoint on 'Evaluating Web Software Reliability Based on Workload and Failure Data Extracted from Server Logs'”,2008. [3] G. Albeanu, A. Averian, I. Duda, “Web Software Reliability Engineering”,2009.

Sprint 1 Goals Read relevant research papers Identify factors that may effect reliability analysis Determine a system to analyze reliability on Identify a metric to analyze reliability Gather access and error logs

Relevant research papers Toan Huynh and James Miller Another viewpoint on "evaluating web software reliability based on workload and failure data extracted from server logs". Empirical Softw. Engg. 14, 4 (August 2009), DOI= /s Jeff Tian, Sunita Rudraraju, and Zhao Li Evaluating Web Software Reliability Based on Workload and Failure Data Extracted from Server Logs. IEEE Trans. Softw. Eng. 30, 11 (November 2004), DOI= /TSE We hope to extend work on these papers

Factors that may effect reliability analysis Byte count User count Session count & errors

System to analyze reliability on Reliability analysis via error logs Variety of reliability requirements Commercial and non-commercial We will try to record the technologies the websites employ (Apache, PHP, Codefusion, etc..)

The Nelson Method R = (n-f)/n = 1 – (f/n) = 1 – r R: Reliability f: Total number of failures n: Number of workload units r: Failure rate Mean Time Between Failures (MTBF) MTBF = (1/f) Σ i t i MTBF = n/f ● Identify a metric to analyze reliability

Access and error logs Universities and companies refusing to provide us with access and error logs. Confidentiality reasons Outsourcing server management to external companies

Sprint 2 Goal Collect enough log files for calculation Automate processes to extra data (user, session, byte, and error counts) and convert them into excel format Log Parser

Sprint 2 Progress A web developer agree to send all logs he has (ASP.NET / DNN)

What is DotNetNuke (DNN) Founded 2006.NET version of Drupal an open source platform for building web sites and web applications based on Microsoft.NET technology. Leading open source ASP.NET web content management system and.NET development framework ~100 employees has been downloaded over 6 million times 5 th Version

Our DNN Logs 10+ Website Window Server (Same Server) SQL Server 2008

Sprint 2 Problems Still looking for logs and may have to consider generating our information

LogParser Microsoft tool designed for parsing text-based logs Flexibility Can output to.csv Ease of bulk parsing